The irony is that it is so easy to track online conversions with a simple pixel or server postback. It's called performance marketing, or affiliate marketing, i

The irony is that it is so easy to track online conversions with a simple pixel or server postback. It's called performance marketing, or affiliate marketing, in the sense that the advertising websites then become what is commonly called an affiliate in online advertising lingo. There really is no reason to pay for impressions these days, unless you believe in a mystical (and suspicious IMHO) quantity known as "branding value".